1. Field of the Invention
The present invention relates to a cooking stove comprising heating means, and in particular, to a cooking stove comprising an operation portion on a top surface of a glass top plate to give an instruction on actuation of heating means.
2. Description of the Related Art
A drop-in type cooking stove is conventionally known in which a cooking stove main body is embedded in an opening formed in a counter top of a system kitchen. In this cooking stove, a glass top plate covering a top surface of the cooking stove main body comprises a capacitive touch switch used to give an instruction on actuation of heating means (see, for example, Japanese Patent Laid-Open No. 10-214677).
The capacitive touch switch is composed of a switch mark printed on a front surface of the glass top plate and an operation circuit board provided in proximity to the part of the back surface of the glass top plate which is opposite to the switch mark. An electrode pattern is formed on the operation circuit board to detect electrical capacitance. The operation circuit board is mounted so that the electrode pattern is located in the part of the back surface of the glass top plate which is opposite to the switch mark. Thus, when a user touches the switch mark, his or her finger, which is an electrostatic object, is detected via the electrode pattern.
Thus, in the conventional cooking stove, the circuit board formed with the electrode pattern is provided in proximity to the back surface of the flat glass top plate. In this case, since the glass top plate and the circuit board are both rigid, it is difficult to dispose the glass top plate and the circuit board so that the back surface of the glass top plate is in tight contact with the circuit board. Consequently, a gap, that is, an air layer is likely to be formed between the glass top plate and the circuit board.
In particular, if a glass top plate strengthened by making the back surface uneven is used, when the back surface of the glass top plate is contacted with the circuit board formed with the electrode pattern, the unevenness of the back surface increases the area of the air layer formed between the back surface and the circuit board. When the air layer is thus present between the back surface of the glass top plate and the circuit board, this may disadvantageously hinder the detection of an electrostatic object located on the front surface of the glass top plate.
It is thus an object of the present invention to provide a cooking stove in which an operation circuit board formed with an electrode pattern is provided on the back surface of the glass top plate so as to suppress the formation of an air layer.